Before you start
Turn the system off at the thermostat. Find the filter at the return-air grille, air handler, or furnace cabinet. If you are unsure where it is, check the equipment manual or ask a technician. You do not need to open electrical panels.
Replace the filter
- Slide out the old filter and note its size. The dimensions are usually printed on the frame.
- Check the airflow arrow on the new filter. It should point toward the equipment, in the direction air travels.
- Slide the new filter into place without forcing it. Make sure the frame sits flat and any access panel closes securely.
- Turn the system back on and confirm air is moving through the vents.
How often should you check it?
Check the filter monthly and replace it when it is dirty or according to the filter and equipment instructions. Homes with pets, construction dust, or heavy system use may need more frequent changes. Use the filter type and size recommended for your equipment; a higher-rated filter is not always better if it restricts airflow.
When to call for service
If airflow stays weak, the filter gets dirty unusually fast, the system freezes, or it will not heat or cool properly, a filter change may not solve the underlying issue. Pillar Mechanical can inspect the system and explain the next step.